Bosnia-Herzegovina's autonomous Serbian region says it will halt cooperation with the state court, prosecutor's office, and police in objection to the arrest of war crimes suspects.

The government in the largely ethnic Serbian Republika Srpska made the announcement on December 10, hours after the state police arrested five ethnic Serbs suspected of committing crimes again non-Serbs during the 1992-95 Bosnian war.

The local parliament endorsed the government's decision by a narrow majority.

The move comes as Republika Srpska threatens to hold a referendum on the jurisdiction of Bosnia's national court, deepening concern in the West over the integrity of the highly decentralized country 20 years after it emerged from the Bosnian war.

After the conflict, Bosnia-Herzegovina was established as a state consisting of two largely autonomous entities -- the Muslim-Croat Federation and Republika Srpska.

The European Union in a statement said the Republika Srpska's decision to suspend cooperation "could jeopardize the functioning of the judiciary and law enforcement," and called on all sides to "respect the rule of law" and "maintain cooperation and dialogue."